The number of echoes combined into a single image or image set in multiple echo imaging sequences or echo-train techniques such as rapid acquisition with relaxation enhancement (RARE), fast-spin echo (FSE), and turbo spin-echo (TSE). In RARE imaging, the ETL typically equals the acceleration factor.
As for tooth pain, it is caused by a reaction of the nerves inside a tooth's pulp chamber with the severity dependent upon the type and degree of the stimulus. What follows are some examples of symptoms you may be feeling and their possible causes.
Cavities form in the roots and surface areas of a tooth. They are generally caused from a lack of proper oral health care, such as cleaning and brushing. They can also be caused from excessive consumption of sugary drinks and snacks. Cavities are a leading cause of headache pain.